Plasticized resin compositions



methylene-containing agents.

Patented July 31, 1945 Harry Kline,

North Plainfleld, N. 1., assignor to Bakelite Corporation, New York, N. Y a corporation of New Jersey 7 Claims.

This invention relates to phenolic resin var-- 'nishes incorporating plasticizing agents to impart flexibility;

In general phenolic resins used in varnishes intended as binders for the manufacture of laminated materials are of a nature yielding material that is lacking in flexibility. To improve the flexibility, plasticizing agents are included which are compatible with thevarnishes, i. e. solvent solutions of the resin; by so doing the laminated materials are made available for stock that can be punched or sheared into various shapes for insulation and the like. Plasticizers commonly used include certain vegetable oils as tung oil and alkyl phthalates. Such plasticizers, however, have a decidedly destructive effect on water resistance which is a property of prime importance for electrical insulating parts; furthermore, they are apt to injuriously modify the electrical properties of the laminated material.

According to the present invention there is incorporated with phenolic resins or solutions thereof, as hereinafter described, alkyl esters of rosin or abietic acid and preferably methyl abietate. These have been found to be compatible with the phenolic resins or their solutions in amounts required for producing laminated with good punching characteristics and in addition imparting improved electrical properties and resistance to water and alkalies as compared with the known plasticizers. For obtaining these effects more than 10 percent and generally from to 30 per cent of the methyl abietate'based on the weight of the Drawing. Application May 16, 1941,

Serial No. 393,775

but ammonia is preferable as it leaves no undeslrable' residue in the resin. The mass was refluxed for '70 minutes at 100 C. and then dehydrated in the usual way with vacuum and finally dissolved with 4230 grams of alcohol. The resulting varnish had a viscosity of 638 centipoises and contained approximately 60 per cent resin. To 6000 parts of the above varnish containing 3600 parts of resin there was then added 1260 parts of methyl abietate and the resulting mass refluxed for one hour. The final varnish had a viscosity of 514 centipoises. l

The ratio of cresol to formaldehyde mentioned above can be varied widely and in place of cresol xylenols or mixtures of cresols and phenol or xylenols and phenol can be used.

Example 2.--As an example of adding abietates to a varnish incorporating a resin made with mine other nitrogenous total resinous content is required; above 30 per cent there is a tendency for the plasticizing agent to separate from the composition. I

The effectiveness of alkyl esters of abietic acid has been found to be most marked in conjunction with the phenolic resinsprepared from cresols or xylenols with formaldehyde or equivalent A further marked improvement, particularly as to water resistance, has been obtained by the incorporation of such agents in the resins of the-character described in Patent No. 2,151,975, March 28, 1939; and prepared with alkyl amines o'r'nltrogenous base catalysts.

Specific illustrations of this invention are the following:

Example 1.-As an example of adding abietates to the usual ammonia catalyzed resinvarnishes, a resin was prepared byreacting 6000 grams of cresol with 4680 grams of 37% aqueous'formalde lwde in the presence of 210 grams of ammonia; other basic catalysts as NaOH can be substituted special amines as described in U. S. Patent No. 2,151,975, 100 parts 1 cresol or commercial xyleno], 80 parts. of 3775 aqueous formaldehyde, and 0.3 part of 33% sol tion of trlmethylamine were refluxed for minutes and the batch was then dehydrated with vacuum in the usual manner and dissolved with alcohol as before to produce a varnish of 60 per cent solids; in place of trimethylaas diethylamine, trlethylamine, triamylamine,

etc., or more generally a catalyst of the formula (alkyl): N-R where R is hydrogen or an alkyl radicaL. Methyl abietate was added in the same ratio as before and the batch refluxed for one hour.

The amount of abietate varied between 10 to 30 per cent to give any desired flexibility within this range and alkyl abietates other than methyl can be used thou h not as efl'ectively.

The above varnishes were paper, such as 6 mil alpha-cellulose, in the usual manner. The impregnated sheets were stacked and submitted to a pressure of 1200 pounds per square inch and a temperature corresponding to pounds steam for 30 to 50 minutes whereupon the varnish sets to the infusible insoluble form. Laminated of any desired thickness can be obtained by varying the number of sheets.

To show the improved water resistance the following results were obtained with samples of laminated material 1 inch by 3 inches immersed used. can be widely in water at room temperature for 24 hours: no

described in Example 1 and including in equivabase catalysts can be used used to impregnate v lent amounts the commonly used plasticizers as well as one without any plasticlzer, added.

or Per For in: W. rem Wk win ht alter 88in 24 cum 1E mches water. room water. room temp. temp.

Laminated with varnish made as in Example 1.... 4a 8 (1.081 0.003 1.95 Laminated with varnish made as in Example 3.... 47.5 .077 .002 1.17 laminated with varnish using tungoil as plaaticizer 4a mi cm 3 Laminated with varnish using an alkyl phthalato as pnsti .i alto .ceo .006 2 i Varnish without any plnssiciser 48.9 .059 .062 1. 1-29 group consisting of cresols, xylenols, mixtures of cresols andphenoi, and mixtures of xylenols and phenol; and a plasticizer for the product comprising methyl abietnte in amount by weight As indicative ofthe electrical properties 033-- tained with the various types of flexible varnishes the following data are given:

ranging from ten to thirty per cent of the total solids content of the composition.

Varnish composition of heat-hardenahle character useful as a binder for the preparation oilaminated materials comprisingin solution a resinous, nitrogenous base-catalyzed reaction product of formaldehyde and a phenol selected from the group consisting of cresols, xylenols, mixtures of cresols and phenol, and mixtures of sylenols and phenol, and a, plasticizer for the product comprising methyl abietate in amount by weight ranging from ten to thirty per cent of the total solids content of the composition.

Pflwel'fwtor-i flg g 4.-Composition of heat-hardenable character 00 comprising a resinous ammonia-catalyzed reac- 00 1000 3 a tion product of formaldehyde and a phenol se- 9 cycles volts/mil, lected from the group consisting of cresols, xy-

lenols. mixtures of cresols and phenol, and mix- Laminated with varnish Percent Percent Pmm tures of xylenols and phenol, and a. plasticizerg fgzg gfiglz- Y 665 for the product comprising methyl abietate in madeasinExamplol... ass as: ass can amount by weight ranging from ten to thirty gg' ggg mgg g per cent of the total solids content of the comoilasplasticmr 1.3:; 1.30 as? 625 position.

1",? g; v 5. Composition r heat-hardenable character p t llltoplutiniurnn 2M :73 Mo comprising a resinous allwlamlne catalyaed reaction product of formaldehyde and a phenol Typical mechanical properties are as follows: selected from the group consisting of cresols, xy=

Tensile strength Flexural strength Modulus of elasticity 4 sswise, 0 Length Cross mudylmvmmndguinltmmplol I 11,200 11,255 24.020 11,635 160x10- 112x10 W323 fitt'fiiiititii-iuw ii. iii 13:32 hiii @322 iiiiiiii $885 From the above tables it is apparent that varnishes prepared inthc manner as herein described have marked advantages in that they produce laminated materials which are flexible and at the same time resistant to water; the laminated made with the varnish of Example 2, is as fully resistant to water as a straight varnish without-any plasticizer, and far more resistant than the oilplasticized varnish. They have in addition excellent electrical and mechanical properties. The laminated materials made with the varnishes of Examples 1 and 2 have the flexibilities requisite for punching and shearing in the usual manner.

What is claimed is:

1. Varnish composition of. heat-hardenable character useful as a binder for the preparation of laminated materials comprising in solution a resinous, ammonia-catalyzed reaction product of formaldehyde and a phenol selected from the group consisting of cresols, xylenols, mixtures of crawls and phenol, and mixtures of xylenols and lenols, mixtures of cresols and phenol, and mixtures of xylenols and phenol, and a plasticizer for the product comprising methyl abictate in amount by weight ranging from ten to thirty per cent of the total solids content of the composition.

6'. Composition of heat-hardenable character comprising a resinous nitrogenous base-catalyzed reaction product of formaldehyde and a phenol selected from the group of cresols, xylenols, mixtures of cresols and phenol, and mixtures of xylenols and phenol, and a plasticizer for the product comprising methyl abietate in amount by weight ranging from ten to thirty per cent of the total solids content of the composition.

7. Laminated material having as a binder a heat hardened composition of a nitrogenous basecatalyzed phenolic-formaldehyde rosin obtained as a reaction product of formaldehyde and a phenol selected from the group consisting of cresols,

- xylenols, mixtures of cresols and phenol, and mix tures of xylenols and phenol and methyl abietate in amount by weight ranging from ten to thirty 

